Knockout punches are used routinely to create holes in thin layers of material such as the sheet metal found on electrical boxes. Knockout punches are used in conjunction with a draw stud, a ram, and a die which are all used to punch a hole.
The user drills a pilot hole approximately in the center of the area where the final hole needs to be located. The draw stud, which has been attached to the ram, has the die slid over its free end until the die abuts the ram. The draw stud is then inserted with its free end first through the pilot hole until the die is seated against one side of a sheet of material. The knockout punch, which has a central hole with internal threads, is screwed onto the free end of the draw stud which has complimentary-shaped external threads on it. This process continues until the knockout punch impinges onto the side of the sheet of material opposite the side on which the die is located. As a result, the sheet of material is snugly captured on both sides by the die and the punch. Finally, the ram is actuated such that the draw stud and knockout punch are drawn toward the ram, supplying sufficient force to the knockout punch to puncture and cut the sheet of material and produce the final hole.
The ram that is used is usually mechanically or hydraulically powered, but can be powered by other means. Overall, this device works well, however, the most time consuming task is screwing the knockout punch onto the draw stud, which can take as long as thirty to sixty seconds to accomplish depending on the length of the draw stud. Of course, this can be frustrating and inefficient for the user, especially when a great number of holes need to be punched. Accordingly, there has been a need to find a way to couple the knockout punch to the draw stud in a faster manner.